Did this issue seem to be a problem for every bike that was during these two years, or did it seem like it was only a "bad batch" for some of the bikes that were released?

For those that had there bikes repaired with this issue, did you get the exact same new valves put back in, or did yamaha find a solution to this and issue slightly different parts to correct this problem with bikes that were still in warantee? Have you continued to have this problem after you put new valves in the bike?

I am asking this because I am looking at an 07 with 9000 miles. I will inspect the vavle stem for wear by looking through intake. But, if everything seems to be ok, I am still curious if this problem may occur later down the road?

Most of the problems regarding this seem to be happening on bikes with a lot less miles than 9000. So Im guessing that if it hasnt had any problems with this issue thus far, I may be in the clear? Is this a reasonable assumption, suggesting that I am not looking at a bike that had "glitches"?

Thank You for all the help, I am new to the forums but have been riding yamaha bikes since 3rd grade

I think there are far more 07-08's that have not had an issue. You always here about the problems but you never really hear, "my bike has xxxx miles and its still going strong." With that said, my 08 has had no engine maintenance and is @ 17850 tonight.
I do believe there is an unusual amount of problems, but not quite as bad as some think.

I have an 07 with around 31,600 and have had no issues. The only time I don't ride it is when it snows otherwise it has seen all condition. Plus I'm not gentle with it although I don't bounce it off the limiter.

13k, no troubles yet even tho some people say that the production date bikes 02/07 are the ones with the most likelihood of having that problem( my PY). Im still going to change them up in the spring out of precaution, better safe then sorry.

I love my bike too much to have this mint beauty have a valve break while I'm cruising around.....